1. Field of the Invention
This invention generally relates to the field of electric power generation, and more particularly to a mobile, under-the-hood power generation system having a generator driven by a motor vehicle engine for producing substantial well-regulated electrical power.
2. Description of Related Art
The need for mobile commercial-grade AC power comes in many applications and cuts across many industries. There is an emerging need for a mobile power generation system that can satisfy the demands of power hungry machinery, like heavy construction tools, while still being capable of delivering well-regulated power to sensitive equipment, like computers. Moreover, not only should the mobile system have the capacity to generate such power while operating at a stationary site, it should also provide the same type of power while the system is in transit. For example, a mobile power generation system should be versatile enough to support the power requirements of emergency response vehicles rendering life-saving services while in transit, as well as satisfy the power demands of sensitive intelligence/news-gathering computer and telecommunications equipment in isolated regions of the world.
There exist various types of mobile power generation systems in the prior art. The most common prior art systems, capable of providing useful, appreciable power, are the portable self-contained generation units. Although these self-contained systems cannot generate power while in transit, they are mobile in the sense that they can be transported to a stationary site in need of electrical power. These self-contained systems usually provide from 2.5 to 10.0 kW of power and are primarily used as residential emergency back-up power systems, remote site primary power installations, building/construction temporary power, and emergency response systems.
These self-contained systems generally rely on a prime mover, such as a small gasoline engine (e.g., 2-20 hp), to supply the mechanical energy that is ultimately converted into electrical power. The small engine is coupled to the input shaft of the generator unit and the power regulation circuitry connects to the electrical generator unit to provide 120-240v, 60 Hz AC output power. Characteristically, the generator units in these conventional portable systems are synchronous AC alternators with rotors that rotate at a constant frequency within the stator windings. By maintaining a constant rotor frequency, the frequency of the alternator electrical output power also remains constant. The rotor frequency, and hence the speed of the gasoline engine, is selected to ensure that the frequency of the electrical output power remains reasonably constant at 60 cycles per second (Hz). This frequency complies with the standard household electrical frequency provided by electrical utilities. The horsepower rating of the gasoline engine must then be selected in a manner that maintains a constant RPM irrespective of the load placed on the engine by the generator unit. The load is determined by the present value of the electrical current being developed by the generator unit in response to varying power demands of devices being powered.
Other prior art mobile power generation systems include "under-the-hood" systems which typically operate in conjunction with a motor vehicle's alternator or battery to provide "on-the-fly" power while the vehicle is in transit. The quantity and quality of the output power generated by these systems are constrained by the limitations of the alternator and battery. For example, as of the filing date of this application, there are no known under-the-hood systems that generate a well-regulated output of 60 Hz-120VACwith a 5 kW power rating. Hence, conventional under-the-hood systems are unable to provide the kind of well-regulated, substantial power needed to service both sensitive and power hungry applications. For example. such systems are incapable of generating 120 VAC, 60 Hz, 5 kW power while a vehicle is in transit, irrespective of the vehicle's engine speed.
Another disadvantage and limitation of the conventional portable self-contained generation systems is that, because of the constant frequency requirement, the prime movers (e.g., gasoline engines) must always run at peak power RPMs even though the loads placed on such engines may be minimal or nonexistent. Moreover, the kilowatt equivalent of the rated gasoline engine horsepower must be substantially larger than the maximum kilowatt rating of the generation system in order to ensure that the load transient on the engine do not vary the engine RPM--a necessary component in maintaining a constant electrical output power frequency.
A further disadvantage and limitation of these conventional portable self-contained systems is that they are relatively bulky and heavy in overall size and weight. These physical factors make the handling and movement of such systems by a single person virtually impossible and renders the transport in passenger vehicles unmanageable. Even when separate trailer mounts or truck beds are used to accommodate the transport of such systems, their size and weight may still require many individuals to position the systems in place. Furthermore, even when systems can supply power while in transit, the power is either not of the same magnitude or not of the same conditioned quality as during stationary operations.
Yet another disadvantage of these conventional portable self-contained generation systems is that they contain a fuel reservoir for supplying fuel to the prime movers (e.g., gasoline engines). Clearly, these systems cannot be stored or transported in enclosed passenger vehicles unless alternative measures are taken to ensure the adequate ventilation of the system.